Treatment for chronic otitis media often involves surgery, including tympanostomy tubes which provide aeration and allow the penetration of topical medications through the tympanic membrane. Such local drug treatment has been found to be highly effective. However, surgery is expensive and in many parts of the world is not practical, leading to hearing loss and deaths due to otitis media in the developing world. To enhance medical treatment of middle ear disorders, we used sequential selection of phage-display peptide libraries to identify rare, novel peptides that actively cross the tympanic membrane while transporting cargo. Preliminary data indicate that a bacteriophage bearing one of these peptides enters the middle ear at 106 times the rate of an untargeted phage. We propose to extend this work by determining the rate and saturation level of transtympanic transport for all identified peptides. We will evaluate the external ear, tympanic membrane and middle ear after transtympanic peptide exposure, to determine whether there are any adverse effects, and assess the ability of peptides to carry drugs and to influence a middle ear infection. We will also determine whether these peptides cross the human tympanic membrane, and characterize the binding partners that mediate transtympanic transport. The proposed research will lead to an entirely novel paradigm for the treatment of middle ear diseases. Transtympanic drug delivery would achieve higher middle ear drug levels and avoid side- or off-target effects, when compared to systemic medications. This methodology will have widespread applications for the treatment of otitis media and other middle ear conditions.